The present invention relates to a device or tool that can be used to separate modular elements that are connected by a Morse taper. More particularly, the invention relates to such a tool that can be used to disassemble modular orthopaedic elements that have Morse tapers. The invention also relates to a system and method for separating such modular orthopaedic elements, such as orthopaedic implants and orthopaedic trials.
Morse connections are those in which mating male and female ends of two elements are tapered to frictionally interlock when pressed or impacted together. Typical Morse tapers provide male and female ends that are conically or frustoconically shaped. The angle of the frustoconical taper is typically less than about 8°, and typically in the range of about 2-4°, which creates considerable friction to lock the male and female ends together.
Morse connections have been used in the orthopaedic field. U.S. Pat. No. 5,549,703 teaches that “It is known in the art to form a connection between two orthopaedic prosthetic components using a Morse taper or taper lock connection. One of the most common examples of such a connection is the neck of a hip stem that forms a connection with a correspondingly shaped socket in the ball of the femoral head component typically called the femoral head.”
However, problems can arise with using a Morse taper to connect two orthopaedic components or elements. Although the connection is very strong, it is difficult to later separate the two elements without damaging the implant. Thus, it has been difficult to use Morse tapers to connect two orthopaedic elements or components that may later need to be separated. This difficulty renders it difficult to use Morse tapers for orthopaedic trials, and to use Morse tapers for modular components of orthopaedic implants.
The present invention addresses the need for a tool, system and method that effectively loosens a Morse connection between two orthopaedic components without damaging the components of the implant and while maintaining the advantages of a Morse connection. It should be understood that the present invention may be useful in separating orthopaedic elements connected through other connections as well.
In one aspect, the present invention addresses this need by providing a disassembly device for use in separating two orthopaedic components. The disassembly device includes a pair of handles pivotally connected. There is at least one cam on each handle. The cams are opposite to each other. The handles and cams are made of a material suitable for surgical use. The handles are sized and shaped to be manually operable.
In another aspect, the present invention addresses this need by providing an orthopaedic system. The system comprises first and second orthopaedic components and a disassembly tool. The second orthopaedic component is capable of being connected to the first orthopaedic component in a longitudinal end to end relationship. At least one of the orthopaedic components has an open-ended notch. The disassembly tool is used for separating the first and second orthopaedic components. The disassembly tool includes a cam. The notch is sized and shaped to receive the cam when the first and second orthopaedic components are connected. The cam is rotatable in the notch to cause relative longitudinal movement between the first and second orthopaedic components for separation of the first and second orthopaedic components.
In another aspect, the present invention addresses this need by providing a method of separating two connected orthopaedic components. Each of the orthopaedic components has a surface, and at least one of the orthopedic components has a notch open to a surface of the adjacent orthopaedic component when the two components are connected. The method includes inserting a cam in the notch and moving the cam in the notch so that the cam acts against the orthopaedic components to separate the components.